This nutrient-dense veg is part of the same family as onions and garlic being an Allium. They're popular for adding depth of flavour to soups and stews similar to how the other edible alliums are used.
They contain a wide variety of plant compounds that aid the body in maintaining healthy function. One example of this is kaempferol, an antioxidant with multiple studies revealing contributions to the protection against heart disease and some cancers.